docs: def set_trace(host=None, port=None, patch_stdstreams=False):
      """
      Opens a remote PDB on first available port.
      """
      if host is None:
          host = os.environ.get('REMOTE_PDB_HOST', '127.0.0.1')
      if port is None:
          port = int(os.environ.get('REMOTE_PDB_PORT', '0'))
      rdb = RemotePdb(host=host, port=port, patch_stdstreams=patch_stdstreams)
      rdb.set_trace(frame=sys._getframe().f_back)